feat(compiler)!: `foreign` module syntax

[alex-snezhko]

Closes #1052 with modified syntax as discussed in Discord

module A

// use as a submodule
foreign module Namespace binds "namespace" {
  foreign value myFn binds "my_fn": WasmI32 => WasmI32
}

// use as a toplevel module
foreign module Namespace binds "namespace"

foreign value myFn binds "my_fn": WasmI32 => WasmI32